Laura Lily Rosenthal ^1,2,3,4* Carola Grinninger ^1,5 Sarah Marie Ulrich ^1,6 Robert Dalla Pozza ^1,6 Nikolaus Haas ^1,6 Paolo Brenner ^1,5 Michael Schmoeckel ^1,5 Sebastian Michel ^1,2,3,4,7 Christian Hagl ^1,5,7 Jürgen Hörer ^1,2,3,4

• ¹ LMU Munich University Hospital, Munich, Bavaria, Germany
• ² Division for Pediatric and Congenital Heart Surgery, Munich, Bavaria, Germany
• ³ European Pediatric Heart Center, LMU Munich University Hospital, Munich, Bavaria, Germany
• ⁴ Department of Pediatric Heart Surgery, German Heart Center, University Hospital of the Technical University Munich, Munich, Bavaria, Germany
• ⁵ Department of Heart Surgery, Munich, Bavaria, Germany
• ⁶ Devision of Pediatric Cardiology and Intesive Care, Munich, Bavaria, Germany
• ⁷ Partner site Munich Heart Alliance,DZHK, (German Centre for Cardiovascular Research), Munich, Bavaria, Germany

The objective of this study was to examine the impact of ventricular assist device support as a bridge to heart transplantation in children with end-stage heart failure. In light of the limited availability of donor organs, particularly in Europe, the number of children requiring ventricular assist device support is rising at an unavoidable rate.We performed a retrospective cohort study of patients who underwent a single and primary pediatric heart transplantation. Patients were divided into two groups: with pre transplant ventricular assist device (VAD) support and without VAD support. The primary outcome was survival at the follow-up evaluation. The time point designated as "time 0" was defined as the time of heart transplantation. Secondary outcome was examined by mean of univariable and multivariable logistic regression, severity of cardiac disease based on ECMO-support pre VAD-support, mean waiting time for transplantation, mean OR time and mean length of hospital stay before and after transplantation.Results: 144 patients could be included in the final analysis. The cumulative survival rate at follow-up period was 67±10 % in group 1 vs. 60±6 % in group 2 (P=0.769). The mean waiting time (days) on the list was 205±155 in group 1 and 119 ± 69 in group2 (P=0.002). The mean length of hospital stay (days) was 214±209 in group1 and 128±91 days in group2. Early primary-graft-failure was 10% in group1 and 13% in group2. Odds ratio [OR] is as follows: 1.992,95% confidence interval [CI]:0.983-1.007,p=0.266, aortic clamp time per minutes:OR:1.008,95%CI:(0.997-1.019),p=0.164, HLM time per minutes:OR: 0.996,95%CI:(0.991-1.001),p=0.146, Operation time per minutes: OR:1.000,95% CI:(0.995-1.004),p=0.861.The provision of pre-HTx VAD support does not have an adverse effect on the short-and longterm survival of pediatric patients undergoing HTx. A higher mortality rate was observed among children under three months of age with congenital heart disease. The patients who received VAD support were in a critical condition and required more ECMO support. The results demonstrated a statistically significant correlation between prolonged waiting times and length of hospital stay in group1. More homogeneous and adequately powered cohorts are needed to better understand the impact of VAD support on posttransplant outcomes.